"Ophiocordyceps sinensis (syn. Cordyceps sinensis) is a fungus which infects a caterpillar, uses nutrients out of it to create mycelia and replaces its body with a sclerotium. The fungus then sprouts out of the head of the caterpillar. In Chinese the fungus is known as Dōng chóng xià cǎo (Chinese: 冬虫夏草; literally "winter worm, summer grass")." -Wikepedia